Atmospheric Pressure Photoionization Mass Spectrometry

Atmospheric Pressure Chemical Ionization (APPI) is the last arrived in the family of atmospheric pressure ionization methods, for the coupling of mass spectrometry to liquid phase separation techniques. The basic idea was to further extend the fields of application of LC-MS to those molecules not or poorly amenable both for Electrospray (ESI) or Atmospheric Pressure Chemical Ionization (APCI). The present review explores the literature reports so far appeared. After a short introduction with the historical background and the premises for its development we describe the technique, its physical principles and the factors affecting its efficiency. After that the review presents a survey of applications in different fields.